Comparison of high-sensitivity C-reactive protein vs. C-reactive protein for diagnostic accuracy and prediction of mortality in patients with acute myocardial infarction

Abstract

Background The role of chronic inflammation in the pathogenesis of atherosclerosis has been unequivocally proven. However, the prognostic impact of C-reactive protein, a marker of inflammatory response in patients with acute myocardial infarction has not been fully clarified. Furthermore, there is no direct comparison of the diagnostic accuracy of C-reactive protein and high sensitivity C-reactive protein in the acute myocardial infarction population. Methods In this prospective observational cohort study, 344 patients with acute myocardial infarction were enrolled. All-cause mortality was a primary endpoint. Patients were followed prospectively for a median of six years. Results The correlation between high sensitivity C-reactive protein and C-reactive protein ( r = 0.99; P < 0.001) and the diagnostic accuracy (98.6%) was high. The ROC analysis revealed that C-reactive protein and high sensitivity C-reactive protein had a low AUC for prediction of mortality (C-reactive protein: 0.565, 95% CI [0.462–0.669], vs. high sensitivity C-reactive protein: 0.572, 95% CI [0.470–0.675]) or major adverse cardiac events (C-reactive protein: AUC 0.607, 95% CI [0.405–0.660], vs. high sensitivity C-reactive protein: AUC 0.526, 95% CI [0.398–0.653]) when assessed at time point of acute myocardial infarction. In contrast, longitudinal inflammatory risk assessment with serial C-reactive protein measurements in the stable phase of the disease revealed a 100% specificity, 100% negative predictive value, 32% sensitivity and 12% positive predictive value of C-reactive protein to predict long-term mortality. The Kaplan Meier analysis showed a significant survival benefit for patients at low residual inflammatory risk ( P =  0.014). Conclusion C-reactive protein and high sensitivity C-reactive protein provide a similar diagnostic accuracy, highlighting that C-reactive protein might replace high sensitivity C-reactive protein in routine assessments. Furthermore, low inflammatory status during the stable phase after acute myocardial infarction predicts favourable six-year survival.